/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package qunar.tc.bistoury.instrument.client.spring.el;

import java.math.BigDecimal;
import java.math.BigInteger;

/**
 * Increment operator. Can be used in a prefix or postfix form. This will throw
 * appropriate exceptions if the operand in question does not support increment.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @author Giovanni Dall'Oglio Risso
 * @since 3.2
 */
class OpInc extends Operator {

    private final boolean postfix;  // false means prefix


    public OpInc(int pos, boolean postfix, SpelNodeImpl... operands) {
        super("++", pos, operands);
        this.postfix = postfix;
        Assert.notEmpty(operands, "Operands must not be empty");
    }


    @Override
    public TypedValue getValueInternal(ExpressionState state) throws EvaluationException {
        SpelNodeImpl operand = getLeftOperand();
        ValueRef valueRef = operand.getValueRef(state);

        TypedValue typedValue = valueRef.getValue();
        Object value = typedValue.getValue();
        TypedValue returnValue = typedValue;
        TypedValue newValue = null;

        if (value instanceof Number) {
            Number op1 = (Number) value;
            if (op1 instanceof BigDecimal) {
                newValue = new TypedValue(((BigDecimal) op1).add(BigDecimal.ONE), typedValue.getTypeDescriptor());
            } else if (op1 instanceof Double) {
                newValue = new TypedValue(op1.doubleValue() + 1.0d, typedValue.getTypeDescriptor());
            } else if (op1 instanceof Float) {
                newValue = new TypedValue(op1.floatValue() + 1.0f, typedValue.getTypeDescriptor());
            } else if (op1 instanceof BigInteger) {
                newValue = new TypedValue(((BigInteger) op1).add(BigInteger.ONE), typedValue.getTypeDescriptor());
            } else if (op1 instanceof Long) {
                newValue = new TypedValue(op1.longValue() + 1L, typedValue.getTypeDescriptor());
            } else if (op1 instanceof Integer) {
                newValue = new TypedValue(op1.intValue() + 1, typedValue.getTypeDescriptor());
            } else if (op1 instanceof Short) {
                newValue = new TypedValue(op1.shortValue() + (short) 1, typedValue.getTypeDescriptor());
            } else if (op1 instanceof Byte) {
                newValue = new TypedValue(op1.byteValue() + (byte) 1, typedValue.getTypeDescriptor());
            } else {
                // Unknown Number subtype -> best guess is double increment
                newValue = new TypedValue(op1.doubleValue() + 1.0d, typedValue.getTypeDescriptor());
            }
        }

        if (newValue == null) {
            try {
                newValue = state.operate(Operation.ADD, returnValue.getValue(), 1);
            } catch (SpelEvaluationException ex) {
                if (ex.getMessageCode() == SpelMessage.OPERATOR_NOT_SUPPORTED_BETWEEN_TYPES) {
                    // This means the operand is not incrementable
                    throw new SpelEvaluationException(operand.getStartPosition(),
                            SpelMessage.OPERAND_NOT_INCREMENTABLE, operand.toStringAST());
                }
                throw ex;
            }
        }

        // set the name value
        try {
            valueRef.setValue(newValue.getValue());
        } catch (SpelEvaluationException see) {
            // If unable to set the value the operand is not writable (e.g. 1++ )
            if (see.getMessageCode() == SpelMessage.SETVALUE_NOT_SUPPORTED) {
                throw new SpelEvaluationException(operand.getStartPosition(), SpelMessage.OPERAND_NOT_INCREMENTABLE);
            } else {
                throw see;
            }
        }

        if (!this.postfix) {
            // The return value is the new value, not the original value
            returnValue = newValue;
        }

        return returnValue;
    }

    @Override
    public String toStringAST() {
        return getLeftOperand().toStringAST() + "++";
    }

    @Override
    public SpelNodeImpl getRightOperand() {
        return null;
    }

}
